This has come up before. This French BEA document has some diagrams of the Thielert clutches.
Some diagrams are on page 9 of the PDF.
I too recall seeing some configuration which used rubber pads alone. My guess is that rubber is not great for a long life, given the high frequency and severity of the torque pulses. But the Thielert design doesn’t last long anyway…
CD-135 and 155 engines have changed from clutches to torsional dampeners quite a while ago and the gearbox is “inspect” and no longer “replace”.
I’m definintely not a mechanical engineer, so bear with me, but wouldn’t a fluid coupling eliminate that issue?
172driver wrote:
wouldn’t a fluid coupling eliminate that issue?
Yes but it comes with a few downsides, such as quite a bit of mass at a place with a long arm, and 5% or so power loss
Diesels are all about being able to burn the cheaper fuel Jet-A. The long wait to get them is tied to the problems of getting the power to weight ratio right. Cessna experimented with a diesel version of it’s Skylane then withdrew it due to lack of demand.
The ‘new’ aviation substitute for 100LL may be an unleaded fuel that is cheaper…but most think it will be more expensive. How the new 100LL substitute arrives and is priced will largely dictate the future for diesel engines in aircraft.
Cessna experimented with a diesel version of it’s Skylane then withdrew it due to lack of demand.
Not correct. They withdrew it for reasons that are not completely clear. There was a demand for it.
Diesels are all about being able to burn the cheaper fuel Jet-A. The long wait to get them is tied to the problems of getting the power to weight ratio right. Cessna experimented with a diesel version of it’s Skylane then withdrew it due to lack of demand.
The ‘new’ aviation substitute for 100LL may be an unleaded fuel that is cheaper…but most think it will be more expensive. How the new 100LL substitute arrives and is priced will largely dictate the future for diesel engines in aircraft.
That is a largely US picture, however.
In the rest of the world, Jet A1 has the advantage of availability which in most cases translates to a lower price. Often much lower e.g. 1/3.
Admittedly, if you cannot penetrate the US market, your sales will be limited. That is the situation Diamond is largely in today.
They withdrew it for reasons that are not completely clear. There was a demand for it.
If they sold significant number of them, what did they do with the planes they sold after the cessation of support? Did they buy them back from the owners, or do they continue to support them? How many were sold and over what time span?
US AOPA reported that unsold airframes were converted back to Lyco engines.
I don’t even know if one was delivered … It was flown by some magazine editors, who all seemed to like it, and first everybody thought this would be a great breakthrough … For unknown (to me!) reasons they cancelled the whole project. First everybody thought there would be a delay, but at the moment it looks like it’s gone forever ..
One of the few articles:
http://www.aopa.org/News-and-Video/All-News/2015/May/14/Cessna-not-accepting-182-JT-A-orders
There was a demand for it.
I don’t even know if one was delivered
If they had a finished product, and there was a demand, they would have delivered it. Obviously they didn’t have a finished product, AND/OR there was no demand, notwithstanding Marketing saying they had (which is what Marketing are paid to say).
For unknown (to me!) reasons they cancelled the whole project.
Probably the reason was the same one behind why they didn’t deliver many (any?). Usually this is because it didn’t work, or they learned that it might not work for very long… or nobody actually wanted one. In the USA, probably nobody wanted it because diesels are generally pointless out there (fuel is not cheaper, and the technology is unknown).
In business you never cut off your balls because you never know when you might need them, so nobody will say something is abandoned until it is dead, buried, and the whole world can obviously see it. Currently “everybody” thinks China is going to buy 1,000,000,000 diesels so “everybody” wants to be a player and nobody will admit their technology isn’t ready for prime time.
Another factor is that if Cessna leaves behind a trail of “dirt” they have a lot to lose: bizjet sales. One CJ is worth many SEPs. They cannot risk bad press.
